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A near infrared photoelectrochemical (PEC) and colorimetric dual-mode aptasensor was fabricated for efficiently determining osteopontin (OPN). Er-MOFs and Au 2 Pt nanoparticles were successfully synthesized. The gold nanoparticles (AuNPs) modified Er-MOF (Er-MOFs@AuNPs) nanocomposites were introduced into the glassy carbon electrode (GCE) to construct a photoelectrochemical sensing interface. OPN aptamer (Apt1) was immobilized onto the Er-MOFs@AuNPs based photoelectrochemical platform through Au-S bond for the selectively recognizing osteopontin. Au 2 Pt-labeled OPN aptamer (Au 2 Pt-Apt2) was subsequently captured onto the OPN/Apt1/MOFs@AuNPs/GCE surface to form a sandwich sensing interface, leading to an enhancement on the photocurrent response. Interestingly, Au 2 Pt nanozyme which possesses peroxidase activity could produce a solution color change in the presence of 3,3′,5,5′-tetramethylbenzidine (TMB) and hydrogen peroxide. The variations of photocurrent response and absorbance can be employed for the quantitative detection of OPN. Under the optimal conditions, the PEC and colorimetric sensing strategies show linear responses towards OPN in the concentration range of 0.01 ∼ 25 ng mL−1 and 1 ∼ 850 ng mL−1, respectively. The calculated determination limits were 2.6 pg mL−1 and 0.04 ng mL−1. The PEC and colorimetric dual-mode sensing platform can provide no crosstalk results and can be mutually verified, thus effectively improving the accuracy and reliability for the determination of OPN. [Display omitted] • Er-MOFs@AuNPs nanocomposites and Au 2 Pt nanozyme were successfully synthesized • Near-infrared photoelectrochemical response was obtained from the photocurrent variation of Er-MOFs@AuNPs interface • A colorimetric response was obtained from the catalytic oxidation of TMB with Au 2 Pt nanozyme • A PEC and colorimetric dual-mode aptasensor was developed for the high-performance determination of osteopontin [ABSTRACT FROM AUTHOR]

In this work, a novel approach was developed for obtaining a strong three-dimensional network of heat conducting path by filling alumina (Al2O3) and graphene sheets (GR) into poly(ethylene-co-vinyl acetate) (EVA). This unique structure effectively prevents the inter-sheet restacking of graphene sheets and minimizes the thermal contact resistance between fillers and interface. The resultant exhibits a high thermal conductivity of 2.40 ± 0.07 W/m K, which is much higher than single filler at the same loading. Additionally, a strong synergistic effect can also be observed, and three-dimensional schematic models were simulated for this enhancement. [ABSTRACT FROM AUTHOR]

A novel glucose biosensor was fabricated by immobilizing glucose oxidase (GOx) on Ag nanoparticles-decorated multiwalled carbon nanotube (AgNP-MWNT) modified glass carbon electrode (GCE). The AgNP-MWNT composite membrane showed an improving biocompatibility for GOx immobilization and an enhancing electrocatalytic activity toward reduction of oxygen due to decoration of AgNPs on MWNT surfaces. The AgNPs also accelerated the direct electron transfer between redox-active site of GOx and GCE surface because of their excellent conductivity and large capacity for protein loading, leading to direct electrochemistry of GOx. The glucose biosensor of this work showed a lower limit of detection of 0.01 mM (S/N = 3) and a wide linear range from 0.025 to 1.0 mM, indicating an excellent analytical performance of the obtained biosensor to glucose detection. The resulting biosensor exhibits good stability and excellent reproducibility. Such bionanocomposite provides us good candidate material for fabrication of biosensors based on direct electrochemistry of immobilized enzymes. [ABSTRACT FROM AUTHOR]

A controlled synthesis method for preparing narrow-dispersed copper nanoparticles, using water and ethylene glycol as the reaction media respectively, has been reported. In order to obtain pure-phase copper nanoparticles using water, the reaction time of 8 h is essential. Owing to the reduction property of ethylene glycol, the reaction rate using ethylene glycol is higher. In addition, the amount of reduction agent can reduce largely. Polyvinyl pyrrolidone plays great role on the size of copper particles, and the increasing of polyvinyl pyrrolidone concentration attributes to the smaller dimension particles. The mean diameter is about 4 nm when the concentration of polyvinyl pyrrolidone is 0.5 mmol/L. Polyvinyl pyrrolidone acts as the polymeric capping agents in the reaction, preventing the agglomeration of the copper nanoparticles. When water is the reaction medium, Cu2+ complex is reduced to Cu+ complex firstly, and the further reduction of Cu+ forms the pure copper nanoparticle. [ABSTRACT FROM AUTHOR]

Abstract: Multi-walled carbon nanotubes (CNTs) were treated by using mechanochemical reaction method to enhance their dispersibility for producing CNT nanofluids. The thermal conductivity was measured by a short hot wire technique and the viscosity was measured by a rotary viscometer. The thermal conductivity enhancement reaches up to 17.5% at volume fraction of 0.01 for an ethylene glycol based nanofluid. Temperature has no obvious effects on thermal conductivity enhancement for the as prepared nanofluids. With an increase in thermal conductivity of the base fluid, the thermal conductivity enhancement of a nanofluid decreases. At low volume fractions (<0.4vol%), nanofluids have lower viscosity than corresponding base fluid due to lubricative effect of nanoparticles. When the volume fraction is higher than 0.4vol%, the viscosity increases with nanoparticle loadings. The prepared nanofluids, with no contamination to medium, good fluidity, stability, and high thermal conductivity, would have potential applications as coolants in advanced thermal systems. [Copyright &y& Elsevier]

The reverse microemulsion containing cationic gemini surfactant trimethylene‐1,3‐bis(dodecyldimethyl ammonium bromide) (12‐3‐12, 2Br - ) is applied to synthesize ZnS nanospheres. Narrow size distributed ZnS nanospheres with controllable size and uniform morphology are successfully fabricated by direct reaction of ZnCl 2 and Na 2 S in the reverse microemulsion systems. Except for the appearance of large aggregates owing to quantum size effects when the incubation time is 2 h, with increasing the incubation time from 12 to 48 h, the diameter of the ZnS nanosphere can be controlled as 20–25 nm and 140 nm, respectively. X‐ray diffraction (XRD), transmission electron microscopy (TEM), and UV‐visible absorption spectroscopy are applied to characterize the resulting ZnS nanoparticles. In the system used in the present study uniform nanosphere morphology can be synthesized, with the incubation time as an important factor in controlling the size of as‐prepared products. [ABSTRACT FROM AUTHOR]

Abstract: A green method was applied to prepare composites of multi-walled carbon nanotubes (MWNTs) decorated with silver nanoparticles (Ag-NPs). The MWNTs were functionalized by using mechanical ball milling technology in the presence of ammonium bicarbonate. The functionalized MWNTs were decorated with Ag-NPs by the traditional method of using a silver mirror reaction. Scanning electron microscopy (SEM) characterization showed that Ag-NPs distributed uniformly on the walls of MWNTs. The content and size of Ag-NPs could be controlled by adjusting the reducing time. The X-ray diffraction (XRD) patterns demonstrated that the Ag-NPs crystallized well. The resulting Ag/MWNT composites were used to prepare a water based nanofluid. The nanofluid showed higher thermal conductivity compared to that of a nanofluid containing MWNTs with functionalized surfaces. [Copyright &y& Elsevier]

Abstract: A highly sensitive hydrazine sensor was developed based on the electrodeposition of gold nanoparticles onto the choline film modified glassy carbon electrode (GNPs/Ch/GCE). The electrochemical experiments showed that the GNPs/Ch film exhibited a distinctly higher activity for the electro-oxidation of hydrazine than GNPs with 3.4-fold enhancement of peak current. The kinetic parameters such as the electron transfer coefficient (α) and the rate of electron exchange (k) for the oxidation of hydrazine were determined. The diffusion coefficient (D) of hydrazine in solution was also calculated by chronoamperometry. The sensor exhibited two wide linear ranges of 5.0×10−7–5.0×10−4 and 5.0×10−4–9.3×10−3 M with the detection limit of 1.0×10−7 M (s/n =3). The proposed electrode presented excellent operational and storage stability for the determination of hydrazine. Moreover, the sensor showed outstanding sensitivity, selectivity and reproducibility properties. All the results indicated a good potential application of this sensor in the detection of hydrazine. [Copyright &y& Elsevier]

Abstract: Stable ethylene glycol based copper nanofluids were prepared through a two-step method, using polyvinyl pyrrolidone as dispersant, which was vital for the long-term stability of nanofluids. The substantial thermal conductivity enhancements were seen for the obtained nanofluids. For ethylene glycol based copper nanofluids with 0.5vol.% at 50°C, the enhancement ratio was up to 46%. The thermal conductivities depended strongly on the temperature of fluid, and the enhancement ratios increased along with the increasing temperatures. Brownian motions of Cu nanoparticles would play the key role on determining the effects of the temperature on thermal conductivity enhancement of nanofluids. The measured apparent thermal conductivity showed the time-dependent characteristic within 15min. It indicated that the measurement should be made after 15min at least to obtain the true thermal conductivities of ethylene glycol based copper nanofluids. [Copyright &y& Elsevier]

Abstract: Ethylene glycol (EG) based nanofluids containing ZnO nanoparticles were prepared, and the thermal transport properties including thermal conductivity and viscosity were measured. The results show that the thermal conductivity of ZnO-EG nanofluids is independent of setting time from 20 to 360min. The absolute thermal conductivity increases with temperature for different temperatures ranging from 10 to 60°C, while the enhanced ratios are almost constant. The thermal conductivity of ZnO-EG nanofluids depends strongly on particle concentration, and it increases nonlinearly with the volume fraction of nanoparticles. The enhanced value of 5.0vol.% ZnO-EG nanofluid is 26.5%, consistent with the prediction values by the combination of the aggregation mechanism with the Maxwell and Bruggeman models. The facts indicate that there is no magic physics behind nanofluids and the classical theories predict the measurements well. The rheological behaviors of the nanofluids show that ZnO-EG nanofluids with low volume concentrations demonstrate Newtonian behaviors, and for higher volume concentrations nanofluids, the shear-shinning behavior will be observed, because the effective volume fraction of aggregates is much higher than the actual solid volume fraction. [Copyright &y& Elsevier]